Vibrating screen dryer



Filed March 10, 1958 wm Q R 8 Q 9 @v Q Q INVENTOR. "FENCE K IRISH A TTOPNE VS United States Patent VIBRATIN G SCREEN DRYER Lawrence K. Irish,Salem, reg., assignor to Lloyd B. Larsen, Silverton, Oreg.

Filed Mar. 10, 1958, Ser. No. 720,258

2 Claims. (Cl. 263-33) My invention relates to means primarily usefulfor drying relatively small particles such as seed or sand and isespecially concerned with a dryer effective to remove superficial orcontained moisture from such material in an effective fashion.

An object of the invention is to provide a dryer so constituted as toexpose the dried material to the drying agent, such as hot air, in auniform and comprehensive fashion.

Another object of the invention is to provide a vibrating screen dryerin which the material being dried is tumbled about and reorientedrepeatedly in order that the drying is not only effective, but is evenlyaccomplished.

Another object of the invention is to provide a vibrating screen dryerhaving a substantial capacity for the volume of the mechanism.

Another object of the invention is to provide a compact, a simple,vibrating screen dryer in which the material being dried can berepeatedly cycled until the desired degree of dryness has been attained.

Another object of the invention is to provide a vibrating screen dryerin which the drying medium such as hot air or gas is economicallyutilized.

Another object of the invention is to provide a self contained vibratingscreen dryer particularly effective for the purpose.

A still further object of the invention is to provide a vibrating screendryer economical to manufacture and operate and readily serviced andmaintained.

Other objects, together with the foregoing, are attained in theembodiment of the invention and described in the accompanyingdescription and illustrated in the accompanying drawing in which:

The figure is an isometric view of a vibrating screen dryer constructedin accordance with the invention, certain portions of the exterior beingbroken away to disclose important parts of the interior.

While a vibrating screen dryer according to the invention can befabricated in a number of different forms, depending somewhat upon thesurrounding circumstances and the capacities desired and also theespecial material to be dried, it has successfully been incorporated asshown herein primarily for use in drying seed. In this instance there isprovided a frame 6 made up of the customary structural metal shapes andincluding side members 7 and a forward end member or head 8 and arearward end member or head 9. Suitably mounted in the two heads 8 and 9on appropriate anti-friction bearings 11 and 12, is a pair of mountingshafts 13 and 14 between their ends carrying supporting rollers 16.

Resting on the rollers are wearing tires 17 and 18 circumscribing theperiphery of a circular cylindrical drum 19. The metal drum is mountedwith its axis slightly inclined to the horizontal inasmuch as the shafts13 and 14 are similarly inclined, the end of the drum adjacent the head9 being somewhat lower than the end 2,959,407 Patented Nov. 8, 1960 ofthe drum adjacent the head 8. The drum is thus rotatably mounted. It isrotated by a suitable motor 20 connected through a chain 22 to both ofthe shafts 13 and 14 so that the shafts are both rotated in a fashion torevolve the drum 19 in the direction of arrow 23 in the figure. The twoends of the revolving drum are themselves open, but they aresubstantially closed by a stationary but removable extension band 26 onthe heads 8 and a similar band 27 on the head 9 so that a virtually airtight enclosure is provided.

In order that the interior of the drum may be supplied with a dryingagent, the frame 6 serves as a mounting for a suitable burner 31. Thisconveniently is a liquid petroleum gas burner having unobjectionableproducts of combustion and discharges through the head 8 into asubstantially triangular combustion duct 32. The duct is arranged withits apex uppermost to shed any material falling thereon and extends fromthe head 8 substantially throughout the entire length of the drum 19terminating just short of the head 9 at the opposite end thereof. Theduct 32 is made of good heat transmitting material so that it serves notonly as a director for the products of combustion of the burner 31, butalso as a conductor and radiatior of heat derived from the products ofcombustion.

In order that the products of combustion discharging at the far end ofthe duct 32 may be appropriately circulated there is also provided inthe head 8 a duct 34 leading to an exhaust fan (not shown) so that thespent products of combustion near the upper portion of the drum 19 aresuitably withdrawn. When the burner 31 and the exhaust mechanismconnected to the duct 34 are put in operation, there is provided asubstantially complete return circuit for the products of combustionthrough the interior of the drum 19.

Material to be dried is introduced into the interior of the drum througha charging opening 41 provided in the head 8. Usually a conduit of asuitable'sort is provided to extend from a material supply point throughthe opening 41 and into the interior of the drum. So that the receivedmaterial can be properly handled, the interior of the drum 19 for itsentire length is lined with an interior layer of metal (or, in someinstances, insulating material) which is contoured to provide a numberof axially extending fins 42 projecting radially from the interiorperiphery of the drum 19 for a short distance.

Material introduced through the feed opening 41 and falling on theinterior of the drum is trapped between successive fins 42 and is pickedup by the rotation of the drum and carried to an elevated location. Thematerial then falls by gravity or spills from the fins and descendsthrough the warm and dry atmosphere maintained within the drum. Thedrying material does not fall all the way to the bottom of the drum, butrather falls on to the uppermost one of a pair of similar superposedscreens 46 and 47.

The upper screen 46, for example, includes a frame 48 made of structuralshapes over which a foraminous or screen layer 49 is provided. Atintervals in the length of the substantially rectangular screen 46 thereare disposed upstanding baffles 51.. The screen 46 is appropriatelysupported at the ends in that the frame 48 is extended by rods 53 and 54piercing a pitman arm 56. There is another pitman arm at the far end,the assembly at one end of the machine adjacent the head 8 beingsubstantially duplicated adjacent the head 9 at the other end. The rods53 and 54 extend through enlarged openings 57 and 58 in the head 8 andpartake of the motion of the pitman arm 56.

One end of the pitman arm is connected by a flexible joint 57 to abracket 58 outstanding from the head 8.

Preferably the joint 57 includes a substantial rubber sleeve or grommetpermitting vibratory motion of sufficient extent. The other end of thepitman arm 56 is enlarged to provide a strap 61 encompassing aneccentric 62 mounted on the end of a drive shaft 63 carried by a journal64 in the head 8. A similar assembly is provided at the other end of themachine. The shaft 63 between its ends is provided with a pulley 66joined by a belt 67 to a drive pulley 68 on the shaft 69 of a motor 71secured to a bracket 72 on the frame 6.

With this mechanism, when the motor 71 is energized the shaft 63 isrevolved and through the eccentric shaft 61 causes the pitman arms 56 topartake of a vibratory motion. Because of the large degree of freedomprovided by the joint 57 at the remote end of the pitman arm, thevibratory action is imparted to the screen 46. In some instances, themotion is enhanced by a spring 73 abutting the pitman arm 56 and alsoabutting a bracket 74 outstanding from the head 8.

In an entirely similar fashion, the screen 47 at each end is mounted ona pitman arm 76 similarly mounted and driven by a shaft 77 at the farside of the machine, being rotated by an independent motor like themotor 71.

Grain or seeds which fall from the rising fins 42 in the drum and dropthrough the warm air therein are intercepted on the upper screen 46 andare vibrated and turned and tossed by the slightly slanted screen beingconfined axially by the baffles 51. Since the screen 46 is preferablyalso slanted slightly toward the far side of the drum 19, the materialeventually discharges over the far edge 78 of the upper screen 46 andfalls by gravity onto the subjacent lower screen 47. This is extended toproject laterally beyond the edge 78 of the upper screen so as tointercept the falling material longitudinally slanted.

The screen 47 is also inclined downwardly toward the rising side of thedrum 19. The seeds or other materials that have fallen onto the lowerscreen 47 are vibrated, tossed and turned as they traverse the screenuntil they fall over the adjacent edge 79 thereof and then drop back tothe inside of the drum 19. When the material again contacts the drum itis again lodged between successive fins 42 and is again carried towardthe top until it falls by gravity thus completing a cycle.

Because the drum 19 as well as the screens 46 and 47 are slightlyinclined from a high end adjacent the head 8 toward a low end adjacentthe head 9 the material in falling and although confined from time totime by the baffles 51 tends gradually to work toward the remote end ofthe drum 19. Material by the time it reaches the far end is thoroughlydried and is ultimately discharged over the end 81 of the drum. Itfallsinto a duct 82 disposed at the lower end of the band 27 and fallsthrough the discharge opening therein for subsequent collection or use.

The vibrating screen dryer, as described, provides a means forrepeatedly cycling material to be dried so that it periodically fallsfreely through the drying atmosphere and is agitated and turned andreoriented so that it is dried quite evenly. In its traverse through thedrum and over the vibrating screens the material is subjected not onlyto conducted heat from the flowing products of combustion, but also issubjected to a convection current locally set up within the revolvingdrum 19 and especially also to heat radiated from the duct 32.

All forms of heat transfer, therefore, are effective in raising thetemperature of the material so as to drive off any accompanyingmoisture. The evolved moisture together with the products of combustionare continually discharged through the exhaust duct 44 so that a freshatmosphere is always presented to the material being dried.

The ends of the revolving drum 19 are reasonably well sealed by means ofthe bands 17 and 18 which can be removed, at least partially if desired,for inspection or renewal, since a relatively close sometimes frictionfit is maintained with the drum to preclude excessive atmosphericleakage. Since each of the shafts 63 and 77 is driven by a separatemotor, the speed of operation of each of the screens 46 and 47 can beseparately set or adjusted in order that a difierent turning and mixingaction can be provided on each.

Pursuant to the invention there has been provided a vibrating screendryer effective to make economical use of the heat available toeffectuate drying in a uniform fashion of the material passing throughthe dryer. Furthermore, there is provided a mechanism which is simple tomanufacture and maintain and one which makes economical use of the spaceinvolved and which generally attains all of the objects of theinvention.

What is claimed is:

1. A vibrating screen dryer comprising a frame, a drum, means formounting said drum on said frame for rotation about an axis inclined tothe horizontal, a burner on said frame at the high end of said drum, aduct extending from said burner through a part of said drum, an exhaustduct on said frame communicating with the high end of said drum, meanson said frame for rotating said drum, longitudinally extending radialfins mounted on and extending from the inside of said drum, means onsaid frame affording a material inlet to the high end of said drum,means on said frame affording a material outlet from the lower end ofsaid drum, an upper screen in said drum above said duct and inclinedfrom the high end of said drum toward the lower end thereof and inclinedtransversely of said drum, a lower screen in said drum between saidupper screen and said duct and inclined from the high end of said drumtoward the lower end thereof and inclined transversely of said drum in adirection opposite to the transverse inclination of said upper screen,the transversely higher edge of said lower screen being beneath thetransversely lower edge of said upper screen and in the path of materialfalling therefrom, means for mounting said upper and lower screens onsaid frame for vibratory movement, and means on said frame for vibratingsaid screens.

2. A device as in claim 1, in which both of said screens havetransversely extending upstanding baffies.

References Cited in the file of this patent UNITED STATES PATENTS299,683 Sawin June 3, 1884 2,535,109 Wigton Dec. 26, 1950 2,746,865Selzer et al. May 22, 1956 FOREIGN PATENTS 19,795 Great Britain 1889528,511 Great Britain Oct. 31, 1940

